Pole change dynamo-electric machines

ABSTRACT

A pole change dynamo-electric machine with three-phase distributed winding is adapted for reconnection to form either one of two different pole numbers and for operation on either one of two different voltages. The adjacent coils of the winding are divided into N coil groups, N being equal to three times the greater one of the pole numbers. Every twelve adjacent coil groups form a set of coil groups. The beginning and end terminals of the specific coil groups within each set are connected and the rest of the terminals are reconnectable.

BACKGROUND OF THE INVENTION

The present invention relates to a pole change dynamo-electric machinewith a three-phase stator winding adapted for reconnection to formeither one of two pole numbers having a ratio of 1:2 and adapted forreconnection for operation on either one of two voltages having a ratioof about 1:2.

Pole change dynamo-electric machines, such as three-phase inductionmotors, adapted to have either one of two pole numbers having a ratio of1:2, e.g., either two poles or four poles, have been known which areoperable on a single voltage. Where it is required that such a polechange dynamo-electric machine is operable on either one of twodifferent voltages having a ratio of, for instance, about 1:2, polechange dynamo-electric machines with separate windings for differentpole numbers have been used. Pole change dynamo-electric machines withseparate windings have a large stator core and are hence bulky, andrequire a large amount of copper and making them costly. Moreover,voltages are induced in the winding which are not used, and circulatingcurrents may flow through the winding, depending on the manner ofconnection of the winding, and may cause burning of the winding.

SUMMARY OF THE INVENTION

An object of the invention is to provide a pole change dynamo-electricmachine with a single distributed three-phase stator winding adapted forreconnection to form either one of two pole numbers having a ratio of1:2 and adapted for reconnection for operation on either one of twovoltages having a ratio of about 1:2.

Another object of the invention is to provide a pole changedynamo-electric machine which can be formed by using a stator core, witha single winding, of a standard motor which is mass-produced, and ishence economical and has standardized characteristics.

A further object of the invention is to provide a pole changedynamo-electric machine wherein all the poles formed are real polesrather than image poles, and the winding factor and the performance ofthe rotating machine are improved.

According to the invention, there is provided a pole-changedynamo-electric machine having a stator core provided with slotsreceiving coils of a three-phase distributed winding adapted forreconnection to form either one of two pole numbers having a ratio of1:2 and for reconnection for operation on either one of two voltageshaving a ratio of about 1:2, characterized in that the coils of thewinding are divided into coil groups of a number equal to three timesthe greater one of the pole numbers, each of the coil groups consistingof a coil or coils arranged in adjacent positions and having a beginningterminal and an end terminal, every twelve adjacent coil groups forminga set of coil groups, and the coil groups of each set beingconsecutively numbered in the order of their positions, and thebeginning terminal of the second coil group and the end terminal of theeleventh coil group are connected together, the end terminal of theseventh coil group and the beginning terminal of the tenth coil groupare connected together, and the beginning terminal of the ninth coilgroup and the end terminal of the twelfth coil group are connectedtogether.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Drawings:

FIG. 1 is a developed diagram showing a stator winding of an embodimentof a pole change dynamo-electric machine according to the invention;

FIG. 2 is a connection diagram of the stator winding shown in FIG. 1;

FIG. 3 is a developed diagram showing a stator winding of a modificationof the invention; and

FIGS. 4-7 are connection diagrams showing how the coils are connectedfor different modes of operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now more particularly to FIGS. 1 through 7, there is shown anembodiment of a pole change dynamo-electric machine according to theinvention. The dynamo-electric machine of this embodiment is athree-phase squirrel-cage motor having a stator with three-phase lapwinding, wherein the coils are arranged in twelve slots. FIG. 2 showsthe connections of the coils. The connections of the terminals of thecoils at various modes of operation are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                GENERAL                                                                       CONNEC-                                                                              CONNECTION TO                                                                            CONNECTION TO                                   SPEED                                                                              VOLTAGE                                                                              TION   POWER SUPPLY                                                                             EACH OTHER                                      __________________________________________________________________________                       RW.sub.3   W.sub.4W.sub.5 W.sub.1Y.sub.2                                                 W.sub.2Z.sub.1                                       HIGH   1 × .increment.                                                                SU.sub.3   U.sub.4U.sub.5 U.sub.1Z.sub.2                                                 U.sub.2X.sub.1                                                     TV.sub.3   V.sub.4V.sub.5 V.sub.1X.sub.2                                                 V.sub.2Y.sub.1                                  HIGH                                                                                             RW.sub.3W.sub.5Z.sub.1                                                                   W.sub.4U.sub.1U.sub.2Z.sub.2                         LOW    2 × .increment.                                                                SU.sub.3U.sub.5X.sub.1                                                                   U.sub.4V.sub.1V.sub.2X.sub.2                                       TV.sub.3V.sub.5Y.sub.1                                                                   V.sub.4W.sub.1W.sub.2Y.sub.2                          HIGH   2 × Y                                                                         RU.sub.2U.sub.4 SV.sub.2V.sub.4 TW.sub.3                                                  ##STR1##                                       LOW                                                                                 LOW    4 × Y                                                                         RU.sub.2U.sub.4U.sub.5X.sub.1 SV.sub.2V.sub.4V.sub.5Y.s                       ub.1 TW.sub.1W.sub.3Z.sub.2                                                               ##STR2##                                       __________________________________________________________________________

In FIG. 1, denoted by numerals 1-12, are slots, in which coils A_(1-A)₄, B₁ -B₄ and C₁ -C₄ are received. The coils have terminals respectivelydenoted by U₁ -U₅, V₁ -V₅, W₁ -W₅, X₁, X₂, Y₁, Y₂, Z₁ and Z₂. Asmentioned above, the stator is shown to have twelve slots, but thenumber of slots may alternatively be 24, 36, 48, or the like. In suchcases, coils received in adjacent slots are connected together toconduct the current of the same phase. For generalization, the coil A₁will be called coil group 51, and similarly the coils A₂ -A₄, B₁ -B₄ andC₁ -C₄ are called 52, 52', 53, 54, 55, 55', 56, 57, 58, 58' and 59, andthese are arranged in the order of first to twelfth coil groups 56, 52,59, 54, 53, 57, 55', 51, 58', 55, 52' and 58, from the left as viewed inFIG. 1. The beginning terminal of the second coil group 52 and the endterminal of the eleventh coil group 52' are connected together to form aterminal U₃. The end terminal of the seventh coil group 55' and thebeginning terminal of the tenth coil group 55 are connected together toform a terminal V₃. The beginning terminal of the ninth coil group 58'and the end terminal of the twelfth coil group 58 are connected togetherto form a terminal W₃.

Where there are 24 coils and each coil group consists of two coils, thetwo coils of each group may be connected in series with each other asshown in FIG. 3. For instance, the coils A₁ and A₁ ' of a group 51 areseries-connected, and the coils C₃ and C₃ ' of a group 58' areseries-connected.

As shown in Table 1, the terminals are adapted for reconnection fordifferent modes of winding connection, and hence for difference modes ofmotor operation.

For instance, for four-pole (low speed) high voltage operation, 2×Ywinding connection is adopted. For this to be achieved, the terminals U₂and U₄ are both connected to a first power supply line R, the terminalsV₂ and V₄ are both connected to a second power supply line S, and theterminal W₃ is connected to a third power supply line T. The terminalsU₃, U₅ and X₁ are connected together, the terminals V₃, V₅ and Y₁ areconnected together, the terminals U₁, X₂, V₁, Y₂, W₅ and Z₁ areconnected together, and the terminals W₁, W₂, W₄ and Z₂ are connectedtogether. The resultant winding connection is as shown in FIG. 4.

For four-pole (low speed) low voltage operation, 4×Y winding connectionis adopted. Then, the terminals U₂, U₄, U₅ and X₁ are all connected tothe first power supply line R, the terminals V₂, V₄, V₅ and Y₁ are allconnected to the second power supply line S, and the terminals W₁, W₃and Z₂ are all connected to the third power supply line T. The terminalsU₁, U₃, X₂, V₁, V₃, Y₂, W₂, W₄, W₅ and Z₁ are all connected together.The resultant winding connection is as illustrated in FIG. 5.

In either of FIGS. 4 and 5, the coil groups 51, 52, 52' and 53 form aU-phase winding, the coil groups 54, 55, 55' and 56 form a V-phasewinding and the coil groups 57, 58, 58' and 59 form a W-phase winding.Thus, the winding arrangement is capable of adoption to either of 2×Ywinding connection and 4×Y winding connection.

For two-pole (high speed) high voltage operation, 1×Δ winding connectionis adopted. Then, the terminals W₃, U₃ and V₃ are respectively connectedto the power supply lines R, S and T. The terminals W₄ and W₅, theterminals W₁ and Y₂, the terminals W₂ and Z₁, the terminals U₄ and U₅,the terminals U₁ and Z₂, the terminals U₂ and X₁, the terminals V₄ andV₅, the terminals V₁ and X₂, and the terminals V₂ and Y₁ arerespectively connected together. The resultant winding connection is asillustrated in FIG. 6.

For two-pole (high speed) low voltage operation, 2×Δ winding connectionis adopted. Then, the terminals W₃, W₅ and Z₁ are all connected to thefirst power supply line R, the terminals U₃, U₅ and X₁ are all connectedto the second power supply line S, and the terminals V₃, V₅ and Y₁ areall connected to the third power supply line T. The terminals W₄, U₁, U₂and Z₂, the terminals U₄, V₁, V₂, and X₂, and the terminals V₄ W₁, W₂and Y₂ are respectively connected together. The resultant windingconnection is as illustrated in FIG. 7.

In either of FIGS. 6 and 7, the coil groups 51, 52, 58' and 59 form aU-phase winding, the coil groups 52', 53, 54 and 55 form a V-phasewinding, and the coil groups 55', 56, 57 and 58 form a W-phase winding.Thus, the winding arrangement is capable of adoption to either of 1×Δwinding connection and 2×Δ winding connection.

Comparison of the winding connections between four-pole operation (FIGS.4 and 5) and two-pole operation (FIGS. 6 and 7) will show that thephases and the polarities of the coil groups 52, 55 and 57 areunchanged, the phases of the coil groups 53, 56 and 58' are changedwhile their polarities are unchanged, the polarities of the coil groups51, 54 and 58 are changed while their phases are unchanged, and thephases and the polarities of the coil groups 52', 55' and 59 are bothchanged.

It will be appreciated that the pole change and voltage change are bothpossible, and the poles formed are real poles rather than image poleseven when the winding is connected to result in four poles. Therefore,the winding factor and the performance of the motor are improved.

The invention has been described with reference to a particularembodiment of the invention, but the invention is applicable to othersituations:

(1) Where Y winding connection is used for the smaller number of polesand Δ winding connection is used for the larger number of poles. Thisarrangement is used to enable speed-change with constant-torque.

(2) Where the winding pitch is different from that of the embodimentdescribed above.

(3) Where wave winding or concentric winding is used, in place of thelap winding.

(4) Where the pole numbers are other than 2 and 4.

For instance, where 4/8 pole-change dynamo-electric machine is desired,the coils are divided into 24 coil groups, every twelve coil groups forma set of coil groups. The coil groups of each set of coil groups areconnected in the same manner as explained in connection with theembodiment described.

It will now be appreciated that the invention provides a pole changedynamo-electric machine having a single stator winding adapted forreconnection to form either one of two pole numbers having a ratio of1:2 and for reconnection for operation on either one of two voltageshaving a ratio of about 1:2. The stator core of a mass-produced standardmotor can be used without modification and even when the winding isconnected to result in the larger number of poles all the poles formedare real poles rather than image poles. Accordingly, the winding factorand the performance of the dynamo-electric machine are improved.Moreover, reduction in size and standardization of the rotating machineare facilitated.

What is claimed is:
 1. In a pole change dynamo-electric machine having astator core provided with slots receiving coils of three-phasedistributed winding adapted for reconnection to form either one of twopole numbers having a ratio of 1:2 and for reconnection for operation oneither one of two voltages having a ratio of about 1:2, the improvementwherein said coils of said winding are divided into coil groups of anumber equal to three times the greater one of said pole numbers, eachof said coil groups consisting of a coil or coils arranged in adjacentpositions and having a beginning terminal and an end terminal, everytwelve adjacent coil groups forming a set of coil groups, and the coilgroups of each set being consecutively numbered in the order of theirpositions, and the beginning terminal of the second coil group and theend terminal of the eleventh coil group are connected together, the endterminal of the seventh coil group and the beginning terminal of thetenth coil group are connected together, and the beginning terminal ofthe ninth coil group and the end terminal of the twelfth coil group areconnected together.
 2. A pole change dynamo-electric machine accordingto claim 1, wherein said winding is adapted for reconnection to formeither two poles or four poles.
 3. A pole change dynamo-electric machineaccording to claim 2, wherein the beginning terminals and the endterminals of said coil groups are reconnected to form a 1×Δ windingconnection for two-pole high voltage operation, 2×Δ winding connectionfor two-pole low voltage operation, 2×Y winding connection for four-polehigh voltage operation, and 4×Y winding connection for four-pole lowvoltage operation.
 4. A pole change dynamo-electric machine according toclaim 1, wherein, in changing the number of poles, the phases and thepolarities of the second, the sixth and the tenth coil groups areunchanged, the phases of the first, the fifth and the ninth coil groupsare changed while their polarities are unchanged, the polarities of thefourth, the eighth and the twelfth coil groups are changed while theirphases are unchanged, and the polarities and the phases of the third,the seventh and the eleventh coil groups are both changed.